I want to build a simple cold forging die to use on an older minster knuckle press. From what I have seen, the dies are usually made by cutting a cavity in the center of a piece of round stock of D2 steel (about 3" dia) and then this round piece is placed inside the center of a second and much larger diameter steel ring (say 12" dia) that has a precision ground inner diameter of about the 3". This ring (called a shrink ring) is heated so that it expands, and then the die is slipped into the inner hole. When everything has cooled you now have your die with a high compressional force on its outside so that it will not crack.

My problem is that making this shrink ring adds a lot of extra work and I would think that someone must make stock shrink rings for this purpose. However I have never found any suppliers that seem to have such rings listed. Maybe they are called something else? I can make a ring if I really need to, but it seems like it would be cheaper to find a stock supplier. I could also make my own allen screws and hex nuts too but obviously it is cheaper and easier to buy such items and I would think it would be the same for a shrink ring.

Thanks for any help on this matter.